1 /* 2 * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved. 3 * Copyright (c) 2019, 2021, Red Hat, Inc. All rights reserved. 4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 5 * 6 * This code is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License version 2 only, as 8 * published by the Free Software Foundation. 9 * 10 * This code is distributed in the hope that it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 13 * version 2 for more details (a copy is included in the LICENSE file that 14 * accompanied this code). 15 * 16 * You should have received a copy of the GNU General Public License version 17 * 2 along with this work; if not, write to the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 19 * 20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 21 * or visit www.oracle.com if you need additional information or have any 22 * questions. 23 * 24 */ 25 26 #include "precompiled.hpp" 27 28 #include "classfile/classLoaderDataGraph.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "code/codeBehaviours.hpp" 31 #include "code/codeCache.hpp" 32 #include "code/dependencyContext.hpp" 33 #include "gc/shared/gcBehaviours.hpp" 34 #include "gc/shared/classUnloadingContext.hpp" 35 #include "gc/shared/suspendibleThreadSet.hpp" 36 #include "gc/shenandoah/shenandoahNMethod.inline.hpp" 37 #include "gc/shenandoah/shenandoahLock.hpp" 38 #include "gc/shenandoah/shenandoahPhaseTimings.hpp" 39 #include "gc/shenandoah/shenandoahRootProcessor.hpp" 40 #include "gc/shenandoah/shenandoahUnload.hpp" 41 #include "gc/shenandoah/shenandoahVerifier.hpp" 42 #include "memory/iterator.hpp" 43 #include "memory/metaspaceUtils.hpp" 44 #include "memory/resourceArea.hpp" 45 #include "oops/access.inline.hpp" 46 47 class ShenandoahIsUnloadingOopClosure : public OopClosure { 48 private: 49 ShenandoahMarkingContext* const _marking_context; 50 bool _is_unloading; 51 52 public: 53 ShenandoahIsUnloadingOopClosure() : 54 // TODO: In non-generational mode, this should still be complete_marking_context() 55 _marking_context(ShenandoahHeap::heap()->marking_context()), 56 _is_unloading(false) { 57 } 58 59 virtual void do_oop(oop* p) { 60 if (_is_unloading) { 61 return; 62 } 63 64 const oop o = RawAccess<>::oop_load(p); 65 if (!CompressedOops::is_null(o) && 66 !_marking_context->is_marked(o)) { 67 _is_unloading = true; 68 } 69 } 70 71 virtual void do_oop(narrowOop* p) { 72 ShouldNotReachHere(); 73 } 74 75 bool is_unloading() const { 76 return _is_unloading; 77 } 78 }; 79 80 class ShenandoahIsUnloadingBehaviour : public IsUnloadingBehaviour { 81 public: 82 virtual bool has_dead_oop(nmethod* nm) const { 83 assert(ShenandoahHeap::heap()->is_concurrent_weak_root_in_progress(), "Only for this phase"); 84 ShenandoahNMethod* data = ShenandoahNMethod::gc_data(nm); 85 ShenandoahReentrantLocker locker(data->lock()); 86 ShenandoahIsUnloadingOopClosure cl; 87 data->oops_do(&cl); 88 return cl.is_unloading(); 89 } 90 }; 91 92 class ShenandoahCompiledICProtectionBehaviour : public CompiledICProtectionBehaviour { 93 public: 94 virtual bool lock(nmethod* nm) { 95 ShenandoahReentrantLock* const lock = ShenandoahNMethod::ic_lock_for_nmethod(nm); 96 assert(lock != nullptr, "Not yet registered?"); 97 lock->lock(); 98 return true; 99 } 100 101 virtual void unlock(nmethod* nm) { 102 ShenandoahReentrantLock* const lock = ShenandoahNMethod::ic_lock_for_nmethod(nm); 103 assert(lock != nullptr, "Not yet registered?"); 104 lock->unlock(); 105 } 106 107 virtual bool is_safe(nmethod* nm) { 108 if (SafepointSynchronize::is_at_safepoint() || nm->is_unloading()) { 109 return true; 110 } 111 112 ShenandoahReentrantLock* const lock = ShenandoahNMethod::ic_lock_for_nmethod(nm); 113 assert(lock != nullptr, "Not yet registered?"); 114 return lock->owned_by_self(); 115 } 116 }; 117 118 ShenandoahUnload::ShenandoahUnload() { 119 if (ClassUnloading) { 120 static ShenandoahIsUnloadingBehaviour is_unloading_behaviour; 121 IsUnloadingBehaviour::set_current(&is_unloading_behaviour); 122 123 static ShenandoahCompiledICProtectionBehaviour ic_protection_behaviour; 124 CompiledICProtectionBehaviour::set_current(&ic_protection_behaviour); 125 } 126 } 127 128 void ShenandoahUnload::prepare() { 129 assert(SafepointSynchronize::is_at_safepoint(), "Should be at safepoint"); 130 assert(ClassUnloading, "Sanity"); 131 CodeCache::increment_unloading_cycle(); 132 DependencyContext::cleaning_start(); 133 } 134 135 void ShenandoahUnload::unload() { 136 ShenandoahHeap* heap = ShenandoahHeap::heap(); 137 assert(ClassUnloading, "Filtered by caller"); 138 assert(heap->is_concurrent_weak_root_in_progress(), "Filtered by caller"); 139 140 ClassUnloadingContext ctx(heap->workers()->active_workers(), 141 true /* unregister_nmethods_during_purge */, 142 true /* lock_nmethod_free_separately */); 143 144 // Unlink stale metadata and nmethods 145 { 146 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_unlink); 147 148 SuspendibleThreadSetJoiner sts; 149 bool unloadingOccurred; 150 { 151 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_unlink_sd); 152 MutexLocker cldgMl(ClassLoaderDataGraph_lock); 153 unloadingOccurred = SystemDictionary::do_unloading(heap->gc_timer()); 154 } 155 156 { 157 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_unlink_weak_klass); 158 Klass::clean_weak_klass_links(unloadingOccurred); 159 } 160 161 { 162 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_unlink_code_roots); 163 ShenandoahCodeRoots::unlink(heap->workers(), unloadingOccurred); 164 } 165 166 DependencyContext::cleaning_end(); 167 } 168 169 // Make sure stale metadata and nmethods are no longer observable 170 { 171 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_rendezvous); 172 heap->rendezvous_threads(); 173 } 174 175 // Purge stale metadata and nmethods that were unlinked 176 { 177 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_purge); 178 179 { 180 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_purge_coderoots); 181 SuspendibleThreadSetJoiner sts; 182 ShenandoahCodeRoots::purge(); 183 } 184 185 { 186 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_purge_cldg); 187 ClassLoaderDataGraph::purge(false /* at_safepoint */); 188 } 189 190 { 191 ShenandoahTimingsTracker t(ShenandoahPhaseTimings::conc_class_unload_purge_ec); 192 CodeCache::purge_exception_caches(); 193 } 194 } 195 } 196 197 void ShenandoahUnload::finish() { 198 MetaspaceGC::compute_new_size(); 199 DEBUG_ONLY(MetaspaceUtils::verify();) 200 }